Surface mount inductors, essential components in Radio Frequency (RF) circuits, often utilize a color-dot coding system to identify their inductance values. Due to their miniature size, deciphering these markings is crucial for proper circuit design and functionality. This article explains how to interpret the Rf Coding on various inductor series.
Single Dot RF Coding
Smaller components like the 0201, 0302, 0402, 0403, and some 0603 series typically lack markings due to space constraints. However, larger 0603 (excluding 0603CT), 0805 (excluding 0805HP), and certain 1008 series inductors feature a single color dot. This dot, located either at the end or in the middle of the component, serves solely for identification and does not indicate polarity. The specific inductance value associated with each color is detailed in the component’s datasheet.
Three Dot RF Coding
Many 1008, 1206, 1812, and Midi Spring series inductors employ a three-dot color code system for denoting inductance. Similar to the single dot, these markings do not indicate polarity. The first two dots represent significant digits of the inductance value in nanoHenries (nH), while the third dot signifies the multiplier (number of zeros to append).
For instance:
- Gray Red Black translates to 82 nH.
- Brown Red Brown signifies 120 nH.
- Yellow Violet Red indicates 4700 nH.
RF Coding for Inductors Below 10 nH
For inductors with values below 10 nH, specifically in series like the 1008CT, 1008HT, 1008HQ, and 1206CS, the third dot doesn’t function as a multiplier. Instead, the combination of all three dots corresponds to a specific inductance value listed in the component’s datasheet. Examples include:
- 1008CT Series: Black Yellow Black represents 4.7 nH, and Black Gray Black represents 8.2 nH.
- 1008HT Series: Black Orange Black equates to 3.3 nH.
Color Code Chart for RF Coding
The following table outlines the numerical value associated with each color in the RF coding system:
0 = Black
1 = Brown
2 = Red
3 = Orange
4 = Yellow
5 = Green
6 = Blue
7 = Violet
8 = Gray
9 = White
Conclusion
Understanding RF coding is paramount for accurately identifying surface mount inductors and ensuring the correct implementation in RF circuits. By deciphering the color dot system, engineers and technicians can effectively select the appropriate components for their designs, leading to optimal circuit performance. Always consult the component’s datasheet for precise inductance values and any series-specific coding variations.
